Choline

Characteristics: Choline is an essential nutrient that occurs naturally in some foods and is available as a dietary supplement. Choline is a source of methyl groups needed for many steps in metabolism. The body needs choline to synthesize phosphatidylcholine and sphingomyelin, two major phospholipids important for cell membranes. Therefore, all plant and animal cells need choline to maintain their structural integrity. In addition, choline is needed to produce acetylcholine, an important neurotransmitter for memory, mood, muscle control, and other brain and nervous system functions. Choline also plays an important role in lipid metabolism and early brain development. Humans can produce choline endogenously in the liver, but the amount naturally synthesized by the body is not enough. As a result, they must obtain a certain amount of choline from their diet. Premenopausal women may need less dietary choline than children or other adults because estrogen induces a gene that catalyzes choline biosynthesis. If the diet is deficient in folate, which is also a methyl donor, the need for dietary choline increases because choline becomes the primary methyl donor.

Absorption: The most common sources of choline in food are the fat-soluble phospholipids phosphatidylcholine and sphingomyelin, as well as the water-soluble compounds phosphocholine, glycerol phosphocholine and free choline. When these choline-containing compounds are ingested, pancreatic and mucosal enzymes release free choline from about half of the fat-soluble forms and some of the water-soluble forms. They are absorbed in the small intestine and stored in the liver, where they are subsequently phosphorylated and distributed throughout the body to form cell membranes.

Dietary Supplements: Choline is available in dietary supplements containing only choline, in combination with B-complex vitamins, and in some multivitamin/multimineral preparations. Typical amounts of choline in dietary supplements range from 10 mg to 250 mg. Supplemental forms of choline include choline bitartrate, phosphatidylcholine, and lecithin. No studies have compared the relative bioavailability of choline from these different forms.

Natural sources: Animal products – meat, poultry, fish, dairy products, and eggs are particularly rich food sources of choline. Choline is present in breast milk and is added to most infant formulas. Cruciferous vegetables, nuts, seeds, and some beans are also good sources of choline. A significant portion of the choline consumed in the diet is in the form of phosphatidylcholine. Many foods contain lecithin, a substance rich in phosphatidylcholine that is prepared during the commercial purification of phospholipids; lecithin is a common food additive used as an emulsifier in processed foods such as sauces, salad dressings and margarine.

Effect: Some studies suggest that choline may protect cardiovascular health by lowering blood pressure, altering lipid profiles, and lowering plasma homocysteine levels. It also slows the onset of degenerative CNS diseases (dementia, Alzheimer’s, and Parkinson's disease) and prevents fatty liver.

Deficiency: Choline deficiency can cause muscle damage, liver damage and non-alcoholic fatty liver disease (NAFLD). Choline deficiency is very rare in healthy, non-pregnant individuals, probably due to the amount the body synthesizes. Approximately 90-95% of pregnant women consume less choline than recommended. Prenatal supplements usually contain little, if any, choline. The risk of choline deficiency may be higher in pregnant and lactating women who do not take folic acid supplements, in women with low levels of vitamin B12.

Recommended daily dose: Adult: 550 mg for men, 425 mg for women (450 mg during pregnancy, 550 mg during breastfeeding).

Adverse Effects: High choline intake is associated with fishy body odor, vomiting, excessive sweating and salivation, hypotension (low blood pressure), and liver toxicity.

Interaction: Not documented.

Pregnancy: No adverse effects have been documented at doses of 550–900 mg/day.

Breastfeeding: Safe in usual doses.

Toxicity: Choline consumption in adults has been shown to increase the production of TMAO (trimethylamine-N-oxide), a substance associated with a higher risk of cardiovascular disease, in a dose-dependent manner.